The invention relates to a method and an apparatus for operating a fiber bale opener, particularly for determining the upper surface boundary of textile fiber bales wherein a fiber tuft detaching (opening) device, provided with at least one rapidly rotating opening roll, is moved above the fiber bales. For measuring the upper surface boundaries, at least two sensors are utilized which are spaced from one another in the travelling direction of the bale opener and which are moved vertically.
According to a known method, the detaching device of the bale opener travels in a horizontal direction above a bale series, that is, the upper surface worked by the detaching device lies in a horizontal plane. The worked-on surface (hereafter also termed a "working surface") and the upper bale boundary of the bale series coincide and both are horizontally oriented. In such a process only the height of the fiber bales, that is, the upper horizontal bale boundary can be determined. Such measurement is effected only once, at the beginning of the detaching process. Thereafter, the stationarily supported fiber bales are abraded in a vertical direction, for example, by means of an opening roll until entire fiber bales are consumed in their entirety. A continuous feed (addition) of new fiber bales to the bales of the series that is worked on, that is, a continuous detaching operation by the fiber bale opener is not feasible.